In Olmstead v. United States, Chief Justice William Howard Taft wrote the decision for a 5-4 majority, finding that evidence obtained by wiretaps was admissible in trials against criminal defendants. Taft reasoned that the wiretaps did not violate the Fifth Amendment's privilege against self-incrimination because the accused were not forced or coerced into their conversation. Additionally, Taft indicated that the wiretaps in question were not in violation of the Fourth Amendment's protection against unreasonable search and seizure because, according to Taft, wiretapping did not constitute a seizure.

"A standard which would forbid the reception of evidence, if obtained by other than nice ethical conduct by government officials, would make society suffer and give criminals greater immunity than has been known heretofore." -- Chief Justice William Howard Taft

Less than 50 years after the Court decision in Olmstead, in part due to the advancements in technologies that made wiretapping a greater issue, Justice Potter Stewart, writing for a 7-1 majority, found that the government had violated the defendant's Fourth Amendment right against unreasonable search and seizure by wiretapping. The Court discarded Taft's reasoning and instead looked to whether the defendant had a reasonable expectation of privacy to determine whether there had been an unreasonable seizure in violation of the Fourth Amendment. If the defendant had a reasonable expectation of privacy, then the government was obligated to obtain a search warrant before wiretapping.

"Wherever a man may be, he is entitled to know that he will remain free from unreasonable searches.and seizures. The government agents here ignored 'the procedure of antecedent justification ... that is central to the Fourth Amendment,' a procedure that we hold to be a constitutional precondition of the kind of electronic surveillance involved in this case." -- Justice Potter Stewart